Image Sensor

This application claims priority to U.S. Provisional Application Ser. No. 63/639,321, filed Apr. 26, 2024, which is herein incorporated by reference in its entirety.

The present invention relates to an image sensor. More particularly, the present invention relates to an enhancement layer and a router layer in the image sensor.

In the field of complementary metal oxide semiconductor (CMOS) image sensor (also known as CIS), quantum efficiency (QE) and angular response would affected the performance of the image sensor. A metasurface layer or a lens layer is usually formed in the image sensor to receive an external light. However, the quantum efficiency and the angular response of the image sensor would be poor when the external light is oblique with respect to an upper surface of the metasurface layer or a lens layer, thereby reducing the performance of the image sensor. Therefore, there is a need to solve the above problems.

The present discloses an image sensor having an enhancement layer, a chromatic dispersion layer, and a router layer. The enhancement layer and the router layer could enhance quantum efficiency (QE) and angular response of the image sensor. A first transverse layer in the enhancement layer and a second transverse layer in the router layer provide additional transverse momentum for a light, so that the light would be more easily guided to the corresponding photodiodes, thereby increasing the performance of the image sensor. The disclosed image sensor allows a larger incident angle of the light propagating in the image sensor, so as to increase the performance of the image sensor.

One aspect of the present disclosure is to provide an image sensor. The image sensor includes a photoelectric conversion layer, a color filter layer, an enhancement layer, a chromatic dispersion layer, and a router layer. The photoelectric conversion layer includes a plurality of photodiodes and a plurality of deep trench isolations separating the photodiodes. The color filter layer is disposed on the photoelectric conversion layer. The enhancement layer is disposed on the color filter layer, wherein the enhancement layer includes a plurality of first pillars, a filling, and a first transverse layer. The plurality of first pillars is disposed on the color filter layer. The filling surrounds the plurality of first pillars, and the filling is disposed on the color filter layer. The first transverse layer is disposed on the plurality of first pillars and the filling. The chromatic dispersion layer is disposed on the enhancement layer. The router layer is disposed on the chromatic dispersion layer, wherein the router layer includes a second transverse layer and a plurality of second pillars. The second transverse layer is disposed on the chromatic dispersion layer. The plurality of second pillars is disposed on the second transverse layer, wherein a critical dimension of the second pillars is smaller than a critical dimension of the first pillars, the critical dimension of the second pillars is defined by a width of a smallest one of the second pillars, and the critical dimension of the first pillars is defined by a width of a smallest one of the first pillars.

According to some embodiments of the present disclosure, a number of the second pillars is greater than a number of the first pillars, and the plurality of first pillars contact the color filter layer.

According to some embodiments of the present disclosure, a refractive index of the first pillars is greater than a refractive index of the chromatic dispersion layer, a refractive index of the second pillars is greater than the refractive index of the chromatic dispersion layer, the refractive index of the first transverse layer is different from the refractive index of the chromatic dispersion layer, and the refractive index of the second transverse layer is different from the refractive index of the chromatic dispersion layer.

According to some embodiments of the present disclosure, the color filter layer includes a first color filter, wherein a thickness of the first transverse layer, a thickness of the second transverse layer, and a thickness of the chromatic dispersion layer are based on the following equations:

wherein his the thickness of the first transverse layer, his the thickness of the second transverse layer, his the thickness of the chromatic dispersion layer, the pixel size is defined by a distance between midlines of two of the deep trench isolations, λ is in a range of a visible light, and the first color filter includes 1 cell of color corresponding to one photodiode, 4 cells of color corresponding to 4 photodiodes, 9 cells of color corresponding to 9 photodiodes, or 16 cells of color corresponding to 16 photodiodes.

According to some embodiments of the present disclosure, the color filter layer includes a first color filter and a second color filter adjacent to the first color filter, a size or a position of one of the first pillars on the first color filter is the same as or different from a size or a position of another of the first pillars on the second color filter.

According to some embodiments of the present disclosure, a refractive index of the first pillars is the same as a refractive index of the first transverse layer, a refractive index of the second pillars is the same as a refractive index of the second transverse layer, and the refractive index of the first pillars is different from the refractive index of the second pillars.

According to some embodiments of the present disclosure, a refractive index of the first pillars is different from a refractive index of the first transverse layer, a refractive index of the second pillars is different from a refractive index of the second transverse layer, the refractive index of the first transverse layer is different from the refractive index of the second transverse layer, and the refractive index of the first pillars is the same as the refractive index of the second pillars.

According to some embodiments of the present disclosure, the first transverse layer includes a plurality of discontinuous portions, the discontinuous portions are spaced apart by the chromatic dispersion layer, each of the discontinuous portions connects each of the first pillars, respectively. A projection of each of the discontinuous portions on the color filter layer laterally beyond a projection of each of the first pillars on the color filter layer.

According to some embodiments of the present disclosure, the color filter layer includes a first color filter, and the first transverse layer has a curved top surface and a flat bottom surface, wherein an upmost thickness of the first transverse layer is based on the following equation:

wherein his the upmost thickness of the first transverse layer, the pixel size is defined by a distance between midlines of two of the deep trench isolations, λ is in a range of a visible light, and the first color filter includes 1 cell of color corresponding to one photodiode, 4 cells of color corresponding to 4 photodiodes, 9 cells of color corresponding to 9 photodiodes, or 16 cells of color corresponding to 16 photodiodes.

According to some embodiments of the present disclosure, the color filter layer includes a first color filter, and the first transverse layer includes a lining layer and a plurality of trapezoids disposed on the lining layer, and a top width of each of the trapezoids is less than a bottom width of each of the trapezoids, wherein an upmost thickness of the first transverse layer is based on the following equation:

wherein his the upmost thickness of the first transverse layer, the pixel size is defined by a distance between midlines of two of the deep trench isolations, λ is in a range of a visible light, and the first color filter includes 1 cell of color corresponding to one photodiode, 4 cells of color corresponding to 4 photodiodes, 9 cells of color corresponding to 9 photodiodes, or 16 cells of color corresponding to 16 photodiodes.

According to some embodiments of the present disclosure, the color filter layer includes a first color filter, and the first transverse layer includes a lining layer and a plurality of trapezoids disposed on the lining layer, and a top width of each of the trapezoids is wider than a bottom width of each of the trapezoids, wherein an upmost thickness of the first transverse layer is based on the following equation:

wherein his the upmost thickness of the first transverse layer, the pixel size is defined by a distance between midlines of two of the deep trench isolations, λ is in a range of a visible light, and the first color filter includes 1 cell of color corresponding to one photodiode, 4 cells of color corresponding to 4 photodiodes, 9 cells of color corresponding to 9 photodiodes, or 16 cells of color corresponding to 16 photodiodes.

According to some embodiments of the present disclosure, a profile of each of the first pillars includes a circle, a square, a hexagon, or a petal shape, each of the first pillars has a first cavity, and a shape of the first cavity includes a circle, a square, or a hexagon. The first cavity is filled with at least a first material different from a material of the first pillars, and an equivalent refractive index of the first pillars is greater than a refractive index of the filling. A profile of each of the second pillars includes a circle, a square, a hexagon, or a petal shape, each of the second pillars has a second cavity, and a shape of the second cavity includes a circle, a square, or a hexagon. The second cavity is filled with at least a second material different from a material of the second pillars, and an equivalent refractive index of the second pillars is greater than a refractive index of a surrounding material.

According to some embodiments of the present disclosure, the color filter layer includes a first color filter and a second color filter adjacent to the first color filter, the first color filter covers two of the photodiodes, and the second color filter covers another two of the photodiodes.

According to some embodiments of the present disclosure, the first pillars have a first global shift relative to the color filter layer, and the second pillars have a second global shift relative to the color filter layer.

According to some embodiments of the present disclosure, the color filter layer includes a first color filter, one of the first pillars above the first color filter has a first inner shift relative to a first alignment line of the first color filter, and one of the second pillars above the first color filter has a second inner shift relative to a second alignment line of the first color filter.

According to some embodiments of the present disclosure, the image sensor further includes a coating layer disposed between the color filter layer and the enhancement layer, wherein the coating layer is conformal or planarized.

According to some embodiments of the present disclosure, the enhancement layer further includes a plurality of third pillars disposed on the first transverse layer, the first pillars and the third pillars are disposed on different sides of the first transverse layer, and the third pillars are spaced apart by the chromatic dispersion layer. The router layer further includes a plurality of fourth pillars disposed on the second transverse layer, the second pillars and the fourth pillars are disposed on different sides of the second transverse layer, and the fourth pillars are spaced apart by the chromatic dispersion layer.

According to some embodiments of the present disclosure, the image sensor further includes a protection layer covering the plurality of second pillars, wherein the protection layer contacts the second transverse layer.

One aspect of the present disclosure is to provide an image sensor. The image sensor includes a photoelectric conversion layer, a color filter layer, a coating layer, an enhancement layer, a chromatic dispersion layer, and a router layer. The photoelectric conversion layer includes a plurality of photodiodes. The color filter layer is disposed on the photoelectric conversion layer. The coating layer is disposed on the color filter layer, wherein the coating layer is conformal or planarized. The enhancement layer is disposed on the coating layer, wherein the enhancement layer includes a plurality of first pillars and a first transverse layer. The plurality of first pillars is disposed on the coating layer. The first transverse layer includes a plurality of discontinuous portions, each of the discontinuous portions has a lens structure, and each of the discontinuous portions connects each of the first pillars, respectively. The chromatic dispersion layer is disposed on the coating layer and surrounds the first pillars and the first transverse layer. The router layer is disposed on the chromatic dispersion layer, wherein the router layer includes a second transverse layer and a plurality of second pillars. The second transverse layer is disposed on the chromatic dispersion layer. The plurality of second pillars is disposed on the second transverse layer, wherein a critical dimension of the second pillars is smaller than a critical dimension of the first pillars, the critical dimension of the second pillars is defined by a width of a smallest one of the second pillars, and the critical dimension of the first pillars is defined by a width of a smallest one of the first pillars.

According to some embodiments of the present disclosure, the image sensor further includes a protection layer surrounding the plurality of second pillars, wherein the protection layer contacts the second transverse layer.

It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the invention as claimed.

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact.

In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. It should be understood that the number of any elements/components is merely for illustration, and it does not intend to limit the present disclosure.

It will be understood that, although the terms “first,” “second,” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a “first element” may be termed a “second element,” and, similarly, a “second element” may be termed a “first element,” without departing from the scope of the embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

is a cross-sectional view of an image sensorA in accordance with some embodiments of the present disclosure. The image sensorA includes a photoelectric conversion layer, a color filter layer, an enhancement layer, a chromatic dispersion layer, and a router layer. The photoelectric conversion layer includes a plurality of photodiodes (PDs)and a plurality of deep trench isolations (DTIs)separating the PDs. The color filter layeris disposed on the photoelectric conversion layer. The enhancement layeris disposed on the color filter layer, wherein the enhancement layerincludes a plurality of first pillars, a filling, and a first transverse layer. The plurality of first pillarsis disposed on the color filter layer. The fillingsurrounds the plurality of first pillars, and the fillingis disposed on the color filter layer. The first transverse layeris disposed on the plurality of first pillarsand the filling. The chromatic dispersion layeris disposed on the enhancement layer. The router layeris disposed on the chromatic dispersion layer, wherein the router layerincludes a second transverse layerand a plurality of second pillars. The second transverse layeris disposed on the chromatic dispersion layer. The plurality of second pillarsis disposed on the second transverse layer.

The photoelectric conversion layerfurther includes a substrate. The PDsand the DTIsare embedded in the substrate. Each of the PDis disposed between two DTIs. In some embodiments, the substratemay be a single structure shared by all of the DTIsand the PDs. The DTIsare configured to avoid light interference and electrical crosstalk between adjacent PDs. The PDsare configured to sense a light L and generate intensity signals according to the intensity of the light L propagating thereon. The intensity signals form the image signals. In some embodiments, the substratemay be a semiconductor substrate, an organic photoelectric conversion substrate, a semiconductor on insulator (SOI) substrate, or another suitable substrate.

The color filter layerincludes a first color filterand a second color filteradjacent to the first color filter. In the embodiment of, the first color filtercorresponds to one PD, and the second color filteralso corresponds to one PD.

In the embodiments of, the first pillarsinclude a pillarand a pillar. The first pillarsand the fillingare disposed between the color filter layerand the first transverse layer. In the embodiment of, the first transverse layeris a continuous layer. Specifically, the first transverse layeris continuously disposed between the first pillarsand the fillingand the chromatic dispersion layer. Both the chromatic dispersion layerand second transverse layerare continuous layers. Specifically, the chromatic dispersion layeris continuously disposed between the first transverse layerand the second transverse layer, and the second transverse layeris continuously disposed between the chromatic dispersion layerand the second pillars. The chromatic dispersion layerseparates the first transverse layerand the second transverse layer. The router layerfurther includes a plurality of recessesdisposed between two second pillars. In the embodiment of, the recessesare filled with air, so the second pillarsis surrounded by the air (i.e. a surrounding material).

The second pillarscould be understood as a metasurface layer, so the image sensorA could be understood as a metasurface-based CIS. Referring to, the second pillarsare configured to receive and disperse the light L. The light L is oblique with respect to an upper surface of the router layer. In other words, an incidence angle θ of the light L is not 0 degree. The light L could be understood as an inclined light. In some embodiments, the incidence angle θ of the light L is in a range from 0 degree to 60 degrees, such as 12 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, or 55 degrees. In the present disclosure, the light L represents a visible light.

In some embodiments, a critical dimension CDof the second pillarsis smaller than a critical dimension CDof the first pillars, wherein the critical dimension CDof the second pillarsis defined by a width of a smallest one of the second pillars, and the critical dimension of the first pillarsis defined by a width of a smallest one of the first pillars, as shown in. In other words, a width of a pillaris smaller than a width of a pillar. The upper pillars (i.e., the second pillars) can route the incoming light L to its corresponding color filters (such as the first color filterand the second color filter) according to the wavelengths of the light L. The smaller sizes of the second pillarsand the larger number of second pillarsare required to make the phases of light L as continuous as possible, so that the light L of different wavelengths has different phase changes with higher energy efficiency, thereby guiding the light L to the corresponding pixels. The lower pillars (i.e., the first pillars) can guide the light L from different incidence angles to the underlying pixels as much as possible, so the larger sizes of the first pillarscan attract the light L from a larger area. In other words, when the critical dimension CDof the second pillarsis smaller than the critical dimension CDof the first pillars, the quantum efficiency (QE) and the angular response of the image sensorA can be enhanced. If the critical dimension CDof the second pillarswas the same as or greater than the critical dimension CDof the first pillars, the function of routing the incoming light L may be reduced and the quantum efficiency (QE) and the angular response of the image sensor may be reduced.

In some embodiments, a number of the second pillarsis greater than a number of the first pillars. When the number of the second pillarsis greater than the number of the first pillars, the function of routing the incoming light L can be enhanced to make the phases of light L as continuous as possible, so that the light L of different wavelengths has different phase changes, thereby guiding the light L to the corresponding pixels. Therefore, the quantum efficiency (QE) and the angular response of the image sensorA can be enhanced. In some embodiments, the plurality of first pillarscontact the color filter layer, as shown in.

In some embodiments, a material of the first pillaris the same as or different from a material of the first transverse layer. In some embodiments, a material of the second pillarsis the same as or different from a material of the second transverse layer. In some embodiments, the refractive index of the first pillarsis the same as or different from the refractive index of the second pillars. In some embodiments, the refractive index of the first transverse layeris the same as or different from the refractive index of the second transverse layer.

In some embodiments, the refractive index of the first pillarsis greater than a refractive index of the chromatic dispersion layer. In some embodiments, the refractive index of the second pillarsis greater than the refractive index of the chromatic dispersion layer. In some embodiments, the refractive index of the first transverse layeris different from the refractive index of the chromatic dispersion layer. In some embodiments, the refractive index of the second transverse layeris different from the refractive index of the chromatic dispersion layer. Since the refractive index of the first transverse layerand the refractive index of the second transverse layerare different from the refractive index of the chromatic dispersion layer, and the refractive index of the first pillarsand the refractive index of the second pillarsare greater than the refractive index of the chromatic dispersion layer, the light L could be deflected in the image sensorA and guided to centers of PDs. In some embodiments, a refractive index of the fillingand the refractive index of the chromatic dispersion layerare less than the refractive indices of the first pillars, the first transverse layer, the second pillars, and the second transverse layer.

In some embodiments, the refractive index of the first pillarsis in a range from 1.4 to 2.6, such as 1.6, 1.8, 2, 2.2, or 2.4. In some embodiments, the refractive index of the second pillarsis in a range from 1.4 to 2.6, such as 1.6, 1.8, 2, 2.2, or 2.4. In some embodiments, the refractive index of the chromatic dispersion layeris in a range from 1.1 to 1.5, such as 1.2, 1.3, or 1.4. In some embodiments, the refractive index of the first transverse layeris in a range from 1.1 to 1.6, such as 1.2, 1.3, 1.4, or 1.5. In some embodiments, the refractive index of the second transverse layeris in a range from 1.1 to 1.6, such as 1.2, 1.3, 1.4, or 1.5.

The arrows illustrated inrepresent an optical path of the light L. Specifically, after the light L transmitting to the second transverse layerthrough the second pillars, the second transverse layerprovide transverse momentum for the light L so that the light L in second transverse layerpropagates along a X axis direction. Next, the light L passes through the chromatic dispersion layerto the first transverse layer, in which the first transverse layerprovide transverse momentum for the light L so that the light L in the first transverse layerpropagates along the X axis direction. Finally, the light L passes through the first pillars, the filling, and the color filter layerto the PDin the photoelectric conversion layerso that the PDcould sense and generate intensity signals of light L. Because the second transverse layerand the first transverse layerprovide transverse momentum for the light L, the light L would be more easily guided to the corresponding PD, thereby increasing the performance (such as QE) of the image sensorA. In other words, compared with an image sensor without a transverse layer(s), the disclosed image sensor with the first transverse layerand the second transverse layercould guide a larger portion of the light L to the corresponding PDs. It is understood that the light L with specific colors corresponds to its specific PDs, respectively.

Still referring to, a thickness hof the first transverse layer, a thickness hof the second transverse layer, and a thickness hof the chromatic dispersion layerare based on the following equations: